In this content, you can learn about introduction of Lathe machine and it's working principle.
LATHE
Lathe is known as mother of all machine tools because it was the first machine tool that lead to the invention of other machines tools. A machine tool is a power driven machine for making articles of a given shape,size and accuracy by removing material from workpieces in the form of chips.
Lathe is a machine tool and it's history dates back to ancient Egypt (around 1300 BC) when Egyptians first developed a two person lathe. Until about 1770 lathes were useless for metal cutting because they lacked power and a holding device strong enough and accurate enough to guide the tool.
Henry Mosley developed the sliding carriage and in 1800 built a screw cutting lathe. Now-a-days lathe has become a general purpose machine tool as it permits a large variety of operations to be performed on it.
Working principle of Lathe
In lathe the workpiece is held between two rigid and strong supports called centres, the cutting tool is rigidly held and supported in a tool post. The cutting or machining of workpiece is achieved by feeding the tool against the rotating workpiece. The single point cutting tool describes a helix tool path by moving linearly while the workpiece rotates.
The tool's axes of movement may be a straight line or they may be along some set of curves or angles but they are essentially linear (in the non mathematical sense). A lathe is used principally to produce cylindrical surfaces and plane surface, at right angles to the axis of rotation. It can also produce tapers if the tool is fed at an inclination.
In general a lathe basically consists of a bed to provide support, a headstock, a cross slide to transverse the tool, a tool post mounted on the cross slide. The spindle is driven by a moter through a gear box to obtain a range of speeds. The carriage moves over the bed guideways parallel to the workpiece and the cross slide provides the transverse motion. A feed shaft and lead screw are also provided to power the carriage and for cutting the threads respectively.
Size and specifications of a lathe
A lathe is specified by the following specifications :-
(1) Height of centres:- The height of the centres is measured over the lathe bed.
(2) Swing over bed:- This is the largest diameter of work that can be turned over the lathe bed.
(3) Swing over carriage or cross slide:- This is the largest diameter of work that can be rotated over the lathe saddle.
(4) Distance between centres:- This specifies the maximum job length in mm that can be held between the centres (headstock & tailstock centres).
(5) Type of bed:- The bed can be straight, semi gap or gap type.
(6)Bed length:- The length of bed is provided in metres and in practice it is the end length of the lathe bed which may include headstock length also.
(7) Spindle bore:- it is diameter of the hole through the lathe spindle for turning bar material.
The other specifications may include:-
(1) Swing in gap (2) Width of bed (3) Spindle speeds range (4) Spindle nose (5) Taper in spindle nose (6) The number of feeds (7) The moter power rating & RPM (8) Metric thread pitches (9) Lead screw pitches (10) Tailstock sleeve travel & (11) Shipping dimensions-length × width & height.
0 Comments